This is one reason i am not a fan of putting ANYTHING critical on the cloud.  It takes one bug..or hack..or mistake and your data is gone.  I posted long ago about what the cloud is.  It isn’t anything revolutionary but de-evolutionary and worse on security.  I’ll quote from the linked article:  

Does the cloud have a place in modern times?  Yes it does.  Personal e-mail i think has a great place.  However businesses with privacy and data security concerns should NOT use the cloud for sensitive communications.  Keep in mind e-mail is akin to shouting outside your building…it is NOT a secure medium.  You have now put your trust in a third party while you still assume all of the responsibility for a breach.  I simply can’t see taking the chance of laws coming down on you while hoping a third party has as much concern about your businesses livelihood as you do.  I can tell you right now. They won’t and they don’t.

So how to avoid this issue?  If you want to put stuff on the cloud make sure you have a local backup of your cloud data OR use another cloud provider to backup your data from your local machine on the other cloud provider.  Isn’t this counter-intuitive?  Isn’t the cloud supposed to be secure and data redundant so this doesn’t happen?  It can’t be and isn’t.

 

Bad news for some people who only live on the cloud: Dropbox has confirmed that a bug in some older version of its desktop app has deleted user files from the cloud.

Good news: Dropbox says that it’s restoring files where it can and is updating the bug. More bad news: it can’t restore all the lost files.

The problem seems to have arisen for users who turned on Selective Sync, which limits cloud syncs to specified folders. These syncs are usually set up to occur after something like a serious crash which has, in a few cases, made the problem incredibly frustrating—a few users seem to have reported that they’ve lost years’ worth of content. Ouch.

If you’ve been affected, Dropbox should be getting in touch, offering a year’s worth of Dropbox Pro service to sooth your soul. But that’s probably little consolation if all your files are gone.

via Dropbox Has Deleted a Bunch of User Files From the Cloud.